Nice diagram but i don't agree with it. In my experience, there aren't 2 populations of owners- irresponsible and not, with no crossover. Sometimes people who would consider themselves definitely in one category (i.e. the responsible one) wake up one day and find they are in the other.. Peoples' circumstances change, they find they can no longer look after their dog, they get ill, divorced, made redundant, goddam it sometimes the pesky buggers even die on us. Voila- a homeless dog, at which point they (the owners, still living ones) wake up and smell the coffee, realising there is nowhere for their beloved pet to go.